Archive for: March, 2010

There's a new optics-related blog out there! A friend and colleague sent me notice that the company he works for, ASE Optics, has started its own blog, called Internal Reflections. Quoting their "about" page,

This blog is a place to share our thoughts on the science and the business of optical engineering.

Some two years ago, I wrote a post about a device called the "whipmag", a thinly-disguised perpetual motion machine based on magnets that would supposedly accelerate without an external source of energy once set in motion. I was understandably critical of the device, and free energy has yet to reach the masses, but that doesn't stop people from being true believers. Last week, I received the following comment on the post (written two years ago, mind you):

Neither the author of this article nor the guy in the second video actually gives any data or analysis applicable to the device in the first video. The author’s diagram does not reflect the structure of the device in the video. Also the author mentions several times “conservation of energy” and “thermodynamics” laws, but does not apply those concepts to explain how the device could not work. Thus no analysis has taken place in this article, only emotional oversimplification ( just like the second video guy ) and a trail of distracting mini history lessons.

The complaint seems to be that I don't actually spend my time proving that the device can't work. My answer to this is that I don't have to! At this point, such devices have been debunked so often and the laws of physics so well understood that the onus is on any would-be perpetual motion discoverer to demonstrate that their device does work, and ideally explain why.

It is especially amusing to hear criticism of "mini history lessons". Science is a process which builds upon all knowledge that has come before; what we have discovered previously -- scientific history -- is crucial. It would be impossible for science to progress if we spent all of our time, in the absence of new evidence, testing schemes that we know have already failed.

With that in mind, it is worth pointing out that perpetual motion has been considered impossible -- and treated with scorn -- for a long, long time. When I dug up the first volume of The Harmsworth Magazine, dated 1899, to seek out a story by Winston Churchill, I also found a popular article on perpetual motion. It is not kind to the concept, or the people who pursue it.

Will the Moon mess up a moon-base? For all the talk of setting up a base of operations on the Moon, it is quite easy to forget that it is a relatively hostile environment. Emma at we are all in the gutter discusses clever attempts to evaluate damage to equipment that was left behind on our previous visits.

Science predicted the Chile’s Earthquake. Finally, Pablo of Astu's Science Blog, who experienced the earthquake in Chile firsthand, explains how science predicted the force and the location of the earthquake remarkably well.

While researching another science post, I came across the following image:

The image is from The Harmsworth Monthly Pictorial Magazine, vol. 1 (1898-1899), at the end of the introduction to the magazine by Alfred C. Harmsworth. This seems to be an early version of an LOLcat, popularized by I Can Has Cheezburger! Though I wouldn't exactly call it "laugh out loud", the picture is a captioned image of cats with the caption in the cat's own voice (hence the "we").

I'm wondering if this is the oldest LOLcat found yet -- the oldest one I'm aware of comes from 1905, seven years after the Harmsworth image.

I've said it before, and I'll say it again -- one finds all sorts of interesting things while wandering through old journals and magazines...

I should remind folks that voting is now open for the ResearchBlogging Awards 2010!
If you are a research blogger and have an account on ResearchBlogging.org, don't forget to vote for your favorite research blogs in a variety of categories, including the Research Blog of the Year, for which I have been nominated!

I would encourage people to vote for me, but I don't want to overstep my bounds and get banned from the awards ceremony and accompanying party. (There is going to be a ceremony and party, right? Right?)

One of the wonderful things about having a career in science is that a deeper understanding of the science leads to a greater appreciation of its beauty. In physics, this usually requires a nontrivial amount of mathematics, but there are some phenomena that are self-evidently beautiful; unfortunately, many of these are also not very well known!

In working on my textbook on optics, I delved rather deeply into one of these phenomena, known as the optical Talbot effect. First observed in 1836 by Henry Fox Talbot, the effect went unnoticed for nearly fifty years before being rediscovered by the great Lord Rayleigh in 1881. The true subtlety of the phenomenon was still not understood, however, for another hundred years!

In short, the Talbot effect can be described as the self-imaging of a diffraction grating: at regular distances from the grating, the light diffracted through it forms a nearly perfect image of the grating itself. This simple statement does not do justice to the Talbot effect, however, which results in stunning images such as:

This is an example of what is known as a Talbot carpet, presumably because it is reminiscent of an ornate Persian rug:

(Why isn't it called a "Talbot rug"? That I can't answer.)

There's a lot to explain in order to understand the significance of the Talbot carpet, starting with an explanation of what exactly a diffraction grating is!

Echoes of the past. We begin with teofilo at Gambler's House, describing fascinating speculation that the former residents of Chaco Canyon may have chosen the site for their home based on its acoustic properties. (I've resolved to visit the site one day.)

The teapot effect, end of. Finally, aimeew at misc.ience shows again how science, in this case physics, is constantly working to make our lives better! Researchers have come up with a solution for "the teapot effect"; I'll let you click through to the link to find out what that is...